Study of Dopamine Transporter Receptor Occupancy With Long-acting Dex-methylphenidate

Study Summary

The objectives of this study are to document the pharmacokinetics of the adequacy of DAT receptor occupancy d-MPH formulation in three doses (20 mg, 30 mg, and 40 mg) using PET scanning with C-11 Altropane as the ligand across a range of times. It has been estimated that MPH is effective when the average CNS DAT occupancy is 50% or greater. Focalin XR has been shown to be clinically effective in an analog classroom as early as 1 hour and as late as 12 hours. Therefore, it is hypothesized that the average DAT occupancy will be adequate (50% or greater) at time periods corresponding to the times of clinical efficacy. The first objective is to examine the onset of action by testing whether average DAT occupancy will be adequate (50% or greater) at 1 hour after dosing for each dose tested (20 mg, 30 mg, 40 mg). The second objective is to test the adequacy of average DAT occupancy in a range of later times for each dose. The times chosen (8, 10 and 12 hours) correspond to times Focalin XR has been shown to be clinically effective in an analogue classroom study. A range of times have been chosen since, while effective at 12 hours, the degree of clinical effectiveness decreased with later time periods. The adequacy of DAT occupancy across this range of time periods will provide important details on the in vivo molecular action of the medicine at periods of critical clinical activity. The third exploratory objective is to examine a time period later then those previously tested with the highest dose. Since the clinical effectiveness of Focalin XR has not been tested out to 14 hours, it is unknown whether it is effective at 14 hours. If Focalin XR were to be effective at 14 hours it would be more likely at the highest dose.

Interventions

• DRUG dex-methylphenidate